Does compost ever go bad?

uscjustoJuly 10, 2013

I have a big compost bin that I bought from HD.
My ingredients have been composting well and the pile inside keeps shrinking. I continue to add browns and greens to it but I rarely take any of the finished compost out.

My question is: does the finished compost at the bottom of the bin ever go bad?

Instead of removing finished compost through the bin door on the bottom, I try to turn the entire bin and mix the bottom finished compost in with the newly added browns and greens.

I should probably get multiple bins but this is the best I can do given the amount of space available. I don't have a need for the finished compost yet, and if I remove the finished compost I will leave the bin with just a small amount of ingredients.

Compost should never go "bad" although if kept too wet it will not be good for the garden until dried out. However, the bacteria that digest it will keep on digesting it so you should use it on the garden before they completely chomp it up in your bin.

It does continue slowly shrinking over time, so it's best to use it fairly soon.

If there is anything at all growing in your yard, put compost on it rather than let it shrink away.

I don't like the doors that much, what I do is lift the bin off (or disassemble into halves if it's that type) and set it up next to the pile. Fork the unfinished stuff off the top back into the bin to start the next batch. When you get down to finished compost, it's easy to scoop up off the ground.

Since you are continuing to add browns and greens and turn but rarely take any finished compost out the decomposition process is continuing.

Do you have a garden? If so why not add the finished compost to it? Then when you don't have enough new materials you can become as weird as the rest of us and be compelled to scrounge more greens and browns! :D

Yes I'm going to start taking out finished compost for the garden and to make compost tea. I'm trying to build a compost screener out of hardware cloth.
However HD sells a whole roll, and I don't need that much.

I'm alreadyike you and scrounge up a lot of greens and browns from gutters, empty fields, and parks.

You can buy hardware cloth in sizes you need from your locally owned hardware store. The big box stores such as Lowes and Home Depot are not known to be all that buyer friendly.
Most every time I need some piece of hardware the locally owned store has it for less then the big box stores do, and because the locally owned hardware store is closer I save on gas.

If fully composted it won't go "bad"...but you'll lose some of it's nutrient effects as it continuously ages, especially N content. As noted, it will also shrink in volume over time as it settles, loses some moisture, and loses some of it's structural stability.

That said, it's effect on mineral soil as an addition is one of it's strongest qualities, anyway.

Though some that rely on composting as an important part of their nutrient regiment might lament the loss of it's overall strength, I find the most value of compost in what it does to soil structure in conjunction with the mineral part of the soil.

For instance, fresh mushroom compost is practically nutrient-bare stuff (1% N/P/K volume at best, usually, and not all of it is available in plant available forms which is a double-whammy). It's one of the "worst" types of composts you can get your hands on as far as nutrient quality goes, but it's effect on soil structure when combined with the mineral portion of the soil is just as good as any other compost.

Some research of spent mushroom media (aka compost, soil, and a host of other names) shows that the soluble (readily available) nutrients are N = 1.5 to 3.0 %, P = 0.5 to 2.0 %, K = 1.0 to 3.0 %, Ca = 8 to 6 %, and Mg = 0.4 to 1.0 %.
Soluble, readily available, does not necessarily mean total nutrients. People have seen much better response in plants growing in spent mushroom media than those numbers would indicate they should.
Over time, as the bacteria continue to digest the compost they will consume some of the nutrients in that compost as well as the material that makes the compost thereby causing that compost to "shrink".